I have been wanting to use TukeyHSD for two and three way aov's, as they are especially simple for students to use correctly. I realize model simplification is usually a preferred methodology, but my disciplinary enertia and simplicity of TukeyHSD is also compelling.
However, the lack of names on the comparisons for the higher order interactions has frustrated us. Here I present a simple, if clumsy work-around to provide names for both the tabluar and plot outputs.
ANY FEEDBACK would be appreciated.
My work-around example:
data(warpbreaks) fm1 <- aov(breaks ~ wool * tension, data = warpbreaks)
a <- TukeyHSD(fm1, "wool:tension") ; a # Gives unlabeled differences
wt <- warpbreaks$tension:warpbreaks$wool # Creates interaction term with the correct order of comparisons
b <-TukeyHSD(aov(breaks~wt,warpbreaks))) # Correctly labels differences , but provides differences that, I think, are slightly inaccurate.
rowames(a) <- rownames(b) # Provides rownames for the correct differences
par(mar=c(5,10,4,2)+0.1) plot(a, las=1) # Puts correct labels on differences.
Thanks for any comments, Hank Stevens
Dr. Martin Henry H. Stevens, Assistant Professor 338 Pearson Hall Botany Department Miami University Oxford, OH 45056
Office: (513) 529-4206 Lab: (513) 529-4262 FAX: (513) 529-4243 http://www.cas.muohio.edu/botany/bot/henry.html http://www.muohio.edu/ecology/ http://www.muohio.edu/botany/
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